Highly fractured and vuggy oil reservoirs represent a challenge for enhanced oil recovery (EOR) methods. The fractured networks provide flow paths several orders of magnitude greater than the rock matrix. Common enhanced oil recovery methods, including gases or low viscosity liquids, are used to channel through the high permeability fracture networks causing poor sweep efficiency and early breakthrough. The purpose of this research is to determine the feasibility of using foam in highly fractured reservoirs to produce oil-rich zones. Multiple surfactant formulations specifically tailored for a distinct oil type were analyzed by aqueous stability and foam stability tests. Several core floods were performed and targeted effects such as foam quality, injection rate, injection type, permeability, gas saturation, wettability, capillary pressure, diffusion, foam squeezing, oil flow, microemulsion flow and gravity segregation. Ultimately, foam was successfully propagated under various core geometries, initial conditions and injections methods. Consequently, fluids were able to divert to unswept matrix and improve the ultimate oil recovery. / text

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Ο τύπος του κατάγματος είναι ένας ανεξάρτητος προδιαθεσικός παράγων για την μεγάλης διάρκειας θνητότητα στους ασθενείς με κάταγμα στην περιοχή του ισχίου. Αφού η μικρής διάρκειας θνητότητα δεν σχετίζεταιμε τον τύπο του κατάγματος,η χειρότερη πρόγνωση στα διατροχαντήρια κατάγματα πιθανά σχετίζεται με έμφυτα χαρακτηριστικά του ασθενούς. / In conclusion the type of fracture is an independent predictor of long-term mortality in patients with hip fractures. Since the short-term mortality was not correlated with the type of the fracture, the worse prognosis of the intertrochanteric type may be probably related to inherent characteristics of patients.

Εισαγωγή: Η θεραπεία των σύνθετων καταγμάτων του άνω πέρατος του βραχιονίου είναι αμφισβητήσιμη και παραμένει ένα θέμα διαρκούς αντιπαράθεσης στη διεθνή βιβλιογραφία. Οι ιδιομορφίες των καταγμάτων αυτών, η μικρή αξιοπιστία και αναπαραγωγικότητα των υπαρχόντων συστημάτων ταξινόμησης, η έλλειψη πολυκεντρικών προοπτικών ερευνών και ο μη καθορισμός αντικειμενικών κριτηρίων αξιολόγησης του θεραπευτικού αποτελέσματος, είναι μερικές μόνο από τις αιτίες που οδηγούν σε ασυμφωνία τους ερευνητές. Η επικρατούσα τάση στη διεθνή βιβλιογραφία σήμερα, επικεντρώνεται στις ελάχιστα παρεμβατικές τεχνικές οστεοσύνθεσης, που περιλαμβάνουν περιορισμένες αποκολλήσεις γύρω από τα κατεαγότα τμήματα, προσπάθεια διατήρησης της αιμάτωσης της κεφαλής και περιορισμό των μεταλλικών υλικών που απαιτούνται για την επίτευξη σταθερής οστεοσύνθεσης. Τα βασικά πλεονεκτήματα της μεθόδου που προτείνουμε είναι η ατραυματική προσπέλαση, η αποφυγή βίαιων χειρισμών επί του κατάγματος, η μη χρησιμοποίηση μεταλλικών υλικών οστεοσύνθεσης, η αποκατάσταση της ρήξης του μυοτενόντιου πετάλου και η χιαστί συγκράτηση των αποσπασθέντων τμημάτων της κεφαλής σε ένα ενιαίο τμήμα, δίκην ταινίας ελκυσμού (tension band effect), που επιτρέπει την σταθερή οστεοσύνθεση του κατάγματος και διευκολύνει την πρώιμη κινητοποίηση του ώμου. Υλικό-Μέθοδος: Την χρονική περίοδο 1991-2003 αντιμετωπίστηκαν χειρουργικά στην κλινική μας με τη μέθοδο της οστεοσυρραφής 214 ασθενείς. Πρόκειται για 123 γυναίκες και 91 άνδρες με πρόσφατο κάταγμα του άνω πέρατος βραχιονίου και μέσο όρο ηλικίας τα 52,7 έτη (από 18 έως 82 ετών). Συνολικά, με βάση την ταξινόμηση και τα κριτήρια του CS. Neer, αντιμετωπίστηκαν 71 κατάγματα 2-τμημάτων, 75 κατάγματα 3-τμημάτων και 64 κατάγματα 4-τμημάτων (48 ενσφηνωμένα σε βλαισότητα) καθώς και 4 περιπτώσεις με κάθετο διαχωρισμό της αρθρικής επιφανείας. Ο μέσος χρόνος παρακολούθησης ήταν 5.2 έτη και αφορούσε το 92% των ασθενών. Συνολικά 13 ασθενείς δεν προσήλθαν στον τελευταίο επανέλεγχο ενώ 4 απεβίωσαν για λόγους μη σχετιζόμενους με το κάταγμα ή την θεραπεία του, αφήνοντας 197 ασθενείς για πλήρη κλινική και ακτινολογική αξιολόγηση. Μελετήθηκαν και αξιολογήθηκαν όλα τα διεγχειρητικά ευρήματα, οι προεγχειρητικές και μετεγχειρητικές ακτινογραφίες, η επάρκεια και διατήρηση της ανάταξης, οι πρώιμες και απώτερες επιπλοκές, τα στοιχεία νοσηλείας, η επίπτωση μετεγχειρητικών φλεγμονών, η συμμόρφωση με το πρόγραμμα φυσιοθεραπείας, η ικανοποίηση του ασθενούς με τη θεραπεία και το τελικό κλινικό αποτέλεσμα, με βάσει τις παραμέτρους του Constant Score. Ακτινολογικά, η εξέλιξη της πώρωσης αξιολογήθηκε με προσθοπίσθια και διαμασχαλιαία ακτινογραφία στον 1ο, 3ο, 6ο και 12ο μήνα, καθώς και στον τελευταίο επανέλεγχο. Η παρουσία πλήρους ή τμηματικής άσηπτης νέκρωσης της κεφαλής, απορρόφησης ή παρεκτόπισης των ογκωμάτων, απώλειας της ανάταξης ή πώρωσης σε πλημμελή θέση, καθώς και οι όποιες ενδείξεις παρουσίας δευτεροπαθούς οστεοαρθρίτιδας και συνδρόμου υπακρωμιακής προστριβής κατεγράφησαν σε όλους τους ασθενείς που συμπεριελήφθησαν στη μελέτη. Σε 16 κατάγματα 4-τμημάτων εκπονήθηκε επιπλέον κλινική αγγειογραφική μελέτη για την διερεύνηση της διατήρησης της αιμάτωσης της βραχιονίου κεφαλής μετά την εφαρμογή της οστεοσυρραφής. Αποτελέσματα: Όλα τα κατάγματα πωρώθηκαν σε διάστημα 10.4 εβδομάδων κατά μέσο όρο (από 6.5 έως 14.6 εβδομάδες), εκτός από τέσσερις περιπτώσεις που παρουσίασαν ψευδάρθρωση. Η μέση τιμή του Constant score κατά τον τελευταίο επανέλεγχο ήταν 80.2 (από 35 έως 100 βαθμούς) ανεξαρτήτως τύπου κατάγματος, ενώ ως ποσοστό επί της λειτουργικότητας του υγιούς ώμου κυμάνθηκε στο 87.5%. Συνολικά 61 ασθενείς (30.9%) είχαν άριστο αποτέλεσμα, 96 (48.8%) πολύ καλό, 24 μέτριο (12.2%) και 16 πτωχό (8.1%). Η συνολική επίπτωση άσηπτης νέκρωσης της βραχιονίου κεφαλής ήταν 22/197 περιπτώσεις (11.1%), με πλήρη καθίζηση της κεφαλής σε 9 ασθενείς και μερική σε 13. Η παρουσία «λύσης» του ΜΒΟ επισημάνθηκε σε 18 ασθενείς (9.1%), έκτοπης οστεοποίησης σε 21 (10.6%), συμπτωματικής οστεοαρθρίτιδας σε 9 (4.5%) και συνδρόμου υπακρωμιακής προστριβής σε 11 (5.5%). Η συνολική επίπτωση επανεγχείρησης λόγω επιπλοκών κυμάνθηκε στο 7.1%. Η ανάλυση των αποτελεσμάτων της αγγειογραφικής μελέτης κατέδειξε διατήρηση της ενδοστικής αιματικής παροχής μετά από την εφαρμογή οστεοσυρραφής στα κατάγματα 4-τμημάτων ενσφηνωμένων σε βλαισότητα. Συμπεράσματα: Προτείνουμε την ανοικτή ανάταξη και εσωτερική οστεοσύνθεση με μη-απορροφήσιμα ράμματα σε όλα τα παρεκτοπισμένα κατάγματα του άνω πέρατος του βραχιονίου που είναι επιδεκτικά οστεοσύνθεσης (2-τμημάτων ΜΒΟ, 3-τμημάτων και 4-τμημάτων ενσφηνωμένων σε βλαισότητα). Αποφεύγοντας τις πιθανές επιπλοκές των μεταλλικών υλικών μπορούμε, με την τεχνική της οστεοσυρραφής, να επιτύχουμε ικανοποιητική ανάταξη, σταθερή οστεοσύνθεση και αποκατάσταση του μυοτενόντιου πετάλου, που επιτρέπουν την πρώιμη κινητοποίηση της άρθρωσης και την επίτευξη ενός καλού τελικού κλινικού και ακτινολογικού αποτελέσματος. Σε νεαρούς ασθενείς με παρεκτοπισμένα κατάγματα 4-τμημάτων χωρίς ενσφήνωση και σε κατάγματα-εξαρθρήματα 3- και 4- τμημάτων, μπορεί να εφαρμοστεί αρχικά η οστεοσυρραφή, με σκοπό την απώτερη βιωσιμότητα της κεφαλής, αλλά η έκβαση είναι λιγότερο προβλέψιμη και η επίπτωση των επιπλοκών σημαντική. / Background: Ideal treatment of displaced proximal humeral fractures remains controversial and a matter of continuous debate in the international literature. The particularities of those fractures, the under strength reliability and reproducibility of the existing classification systems, the lack of multicenter prospective studies and the heterology definitions about the evaluation of results are only some of the reasons that bring researchers out of step. Current trends in operative treatment of these fractures are focused in minimal invasive techniques of reconstruction, involving limited soft tissue detachments, preserving blood supply of the humeral head and eliminating of necessary hard material application for stable osteosynthesis. The main advantages of our proposed technique are the minimal approach, without forced manipulations on the fracture, the avoidance of any hard material application, the repair of coexisting rotator cuff tears and the cruciate, tension-band like manner of bone fragments retention to a uniform part that allows stable internal fixation of the fracture and early shoulder joint motion. Material-Methods: Between 1991 and 2003, 214 patients underwent transosseous suturing for displaced fractures of the proximal humerus in our Department. There were 123 women and 91 men with a mean age of 52.7 years (range, 18-82). According to Neer criteria and fracture classification we managed 71 two-part fractures, 75 three-part and 64 four-part (48 of them was of valgus impacted subtype) as well as 4 splitting head fractures. Mean follow up period was 5.2 years and concerned the 92% of the patients. Overall, 13 patients were lost from the last follow up appointment and 4 died from reasons unrelated to the fracture or its treatment, leaving a total of 197 patients for full clinical and radiological evaluation. We recorded and investigated all preoperative and postoperative radiographs, intraoperative details, kind of reduction, early and late complications, hospital stay details, the incidence of infection, the cooperation with the rehabilitation program, the patient satisfaction and the objective clinical outcome according to the parameters of Constant score. Radiologically, the union progress was evaluated with anteroposterior and auxiliary views at 1st, 3rd, 6th, and 12th month as well as at the last follow up. All radiographs were investigated for the presence of partial or total collapse of the head, lysis or tuberosity displacement, loss of reduction or malunion as well as for signs of post-traumatic osteoarthritis and subacromial impingement syndrome. In 16 patients with four-part valgus impacted fractures, a digital angiographic evaluation was performed for further investigation of humeral head supply after transosseous suturing. Results: All fractures were united until the 10.4 week (range, 6.5 to 14.6 weeks), except four that developed nonunion. The mean Constant score at the last follow up was 80.2 (from 35 to 100 points) singly from fracture type, whereas the functional score as a percentage to that of the unaffected shoulder was 87.5%. Overall, 61 patients (30.9%) were rated as excellent, 96 (48.8%) very good, 24 good (12.2%) και 16 poor (8.1%). The overall incidence of avascular necrosis was 22/197 cases (11.1%); 9 patients showed total collapse and 13 partial collapse. Greater tuberosity lysis was noted in 18 patients (9.1%), heterotopic ossification in 21 (10.6%), posttraumatic osteoarthritis in 9 (4.5%) and subacromial impingement syndrome in 11 (5.5%). The overall rate of reoperation due to complications was 7.1%. The results of angiographic investigation showed conservation of endosteal blood supply of the humeral head, after transosseous suturing. Conclusions: We suggest open reduction and internal fixation in all displaced fractures of the proximal humerus that were amenable for fixation (2-part greater tuberosity, 3-part and 4-part valgus impacted fractures). Avoiding the complications of any hard material application, we are able, with the solely use of transosseous sutures, to accomplish adequate reduction, stable osteosynthesis and repair of rotator cuff tears, allowing for early shoulder joint motion and a satisfactory clinical and radiological outcome. In young patients, with displaced four-part fractures without impaction or 3- and 4-part fractures-dislocations, the transosseous suturing can be applied initially, as a head preserving treatment, but the outcome is less predictable and the rate of complications prominent.

In this research, we study high resistivity fractures found in unconsolidated clay sediments on logging-while-drilling borehole resistivity images from Indian continental margin collected during the National Gas Hydrate Program Expedition 01. These fractures, found at Sites 5, 6, 7, and 10 are likely filled with natural gas hydrate. Gas hydrate is identified on borehole logs and images as high resistivity responses without associated density increases or indications of free gas. The local state of stress at the time of fracturing can be determined by fracture orientations. In Holes 5A, 5B, 6A an 7A the gas hydrate-filled fractures have an aligned, preferred orientation likely associated with a local stress regime. At Site 10, where 130 m of gas hydrate-filled fractures were observed, fracturing is chaotic, likely due to high gas flux.

A flapper valve is made from a hardened and tempered high strength strip steel which opens and shuts as it is subjected to very high cyclic loads. Steel strip of which flapper valves are made from can   encounter a surface defect which are anticipated to influence fatigue life negatively. In this study, the influence of surface scratches on fatigue life of flapper valve strip was investigated. The analysis was carried out by using thirty samples that were blanked out of eight different steel strips in the transverse direction. Of these samples, fifteen of them had scratches on the surface and fifteen did not, all these samples were fatigue tested by constant amplitude method. An S-N curve was plotted based upon the values and results from the fatigue test, considering the curve as the nerve center in relation with fractrographic studies using the Scanning electron microscope. Therefore this master thesis work aims to explain the influence of scratches on fatigue life of flapper valve strip and suggest future improvements based on the findings.

Cell-based therapies have potential for tissue regeneration but poor delivery methods lead to low viability or dispersal of cells from target sites, limiting clinical utility. Here, we developed a degradable and injectable hydrogel to deliver stem cells for bone regeneration. Alginate microbeads <200µm are injectable, persist at implantation sites and contain viable cells, but do not readily degrade in-vivo. We hypothesized that controlled release of rat adipose-derived stem cells (ASCs) from alginate microbeads can be achieved by incorporating alginate-lyase in the hydrogel. Microbeads were formed using high electrostatic potential. Controlled degradation was achieved through direct combination of alginate-lyase and alginate at 4°C. Results showed that microbead degradation and cell release depended on the alginate-lyase to alginate ratio. Viability of released cells ranged from 87% on day 2 to 71% on day 12. Monolayer cultures of released ASCs grown in osteogenic medium produced higher levels of osteocalcin and similar levels of other soluble factors as ASCs that were neither previously encapsulated nor exposed to alginate-lyase. Bmp2, Fgf2, and Vegfa mRNA in released cells were also increased. Thus, this delivery system allows for controlled release of viable cells and can modulate their downstream osteogenic factor production.

Darbe atlikta teorinė mokslinės literatūros analizė, kuri susijusi su motyvacija ir rankų kaulų lūžių tema, bei grindžiami tyrimo rezultatai juos lyginant su mokslininkų panašaus pobūdžio tyrimo duomenimis.Iškelta hipotezė kad, ne tik reabilitacijos priemonės bet ir pačio asmens motyvacija pasveikimui lemia greitesni funkcini nepriklausomumą.Tyrimo tikslas: Nustatyti asmenų, patyrusių rankų kaulų lūžius, motyvacijos ir savarankiškumo kaitą taikant reabilitacija.Siekiant išsiaiškinti, kaip asmenys vertina veiklos atlikimą kasdienėje, darbo ir laisvalaikio srityje buvo naudojamas Kanadietiškas veiklos vertinimo testas. Įvertinti asmenų motyvaciją buvo naudotas Pasveikimo padėties valdymo klausimynas. Tiriamieji taipogi buvo apklausti naudojant anketą, kuri buvo paruošta tyrėjo. / The theoretical analysis of scientific literature related to the motivation and the topic of arm fractures was carried out and the results of the research were based comparing them with the similar research data. A hypothesis is formulated that patient’s functional independence is spurred not only by the measures of rehabilitation but also by person's own motivation to get well.The aim of the research is to define the change of motivation and independence of persons who suffered arm fractures while applying rehabilitation. In order to find out how people evaluate the performance of activity in daily life, at work and at leisure, Canadian Performance Evaluation Test has been used. Recovery Locus of Control questionnaire was given in order to evaluate people’s motivation. The respondents were also questioned using a questionnaire that was prepared by the researchers. 100 patients who suffered different types of arm fractures participated in the research. Change of biosocial skills, independence and motivation while applying rehabilitation has been analysed in the empirical part of the paper.

Background. Diabetes seems to be associated with an increased risk of fractures in the general population. We aimed to determine whether pre-transplant diabetes increases the risk of fractures among patients receiving solid organ transplantation. / Methods. We conducted a nested case-control study in a cohort of subjects 18 years and older who received a first solid organ transplantation in Quebec between January 1st 1986 and July 31st 2005, and who were covered by the RAMQ drug plan at least 1 year before the transplantation and 3 months after the date of discharge from the transplantation hospitalization. Cases were subjects from the cohort who had sustained a fracture between the date of discharge from the hospitalization for transplantation and the end of the study period or the patient's death. The fracture date was the case index date. All incidental fractures were included except fractures of the skull, phalanges of the hand and foot, multiple fractures and pathological fractures, and were identified by medical service claims. Controls were matched to cases on the type of organ transplanted and on the date of the transplantation (+/- 3 months). Crude and adjusted odds ratios (OR) were obtained with univariate and multivariate conditional logistic regression models. / Results. The study included 238 cases and 873 controls. Pre-transplant diabetes was present in 30% of the cases and 22% of the controls (crude OR: 2.16, 95% CI: 1.7--2.8). After adjusting for potential confounders, pre-transplantation diabetes remained a significant risk factor for fractures (adjusted OR: 1.94, 95% CI: 1.5--2.6). / Conclusion. Pre-transplant diabetes appeared to significantly increase post-transplant fractures among adults receiving solid organ transplantation.

Objectives. beta-blockers can alter bone turnover and increase bone formation in animals. It is unknown whether beta-blockers have similar bone protective effects in humans. We aimed to estimate the effects of beta-blockers on bone mineral density (BMD) and fractures using data from the Canadian Multicentre Osteoporosis Study, a large prospective cohort study. / Methods. All medications, including beta-blockers, taken at baseline and after five years of follow-up were recorded. BMD was measured at baseline. During the five years of follow-up, incident minimal trauma fractures were documented by yearly questionnaires. To compare users of beta-blockers to non-users while controlling for possible confounders, multiple linear regression was utilized to estimate between group differences in BMD and multivariate logistic regression was employed to estimate differences in fracture risk. / Results. Of the 9423 participants, 236 of 2884 males (8.2%) and 600 of 6539 females (9.2%) used beta-blockers at some point during the study. In men, beta-blocker users had differences of +1.1% (95% confidence interval [CI] -0.9%, 3.0%) and +1.2% (95% CI -0.5%, 4.0%) in baseline BMD at the total hip and at the lumbar spine, respectively, compared to non-users. In women, beta-blocker users had differences of +0.05% (95% CI -1.2%, 1.3%) and +0.2% (95% CI -1.3%, 1.7%) for the BMD of the total hip and the lumbar spine, respectively, compared to non-users. For users of beta-blockers at baseline, the adjusted odds ratio (OR) for any minimal trauma fracture was 1.23 (95% CI 0.67--2.25) in men and 1.02 (95% CI 0.76--1.35) in women. Chronic use (user at baseline and year 5) in men had an OR for any minimal trauma fracture of 2.1 (95% CI 1.0--4.3). In women who used beta-blockers at baseline but not at year 5, the OR for hip fracture was 6.3 (95% CI 2.0--19.3). The risk of fractures for other sites was inconclusive owing to wide confidence intervals. / Conclusion. Despite relatively large numbers of subjects, wide confidence intervals do not permit strong conclusions with regards to the effect of beta-blockers on BMD in men. Using a 2% limit of clinical importance for BMD, there appears to be no effect of beta-blockers on BMD in women. There is some evidence from our study that beta-blockers may be associated with an increased risk of fractures in certain subsets of users.